Ventilatory support during critical phase result in inactivity of respiratory muscles especially diaphragm muscle. These inactivity also result in change of contractile capability and quick muscular atrophy.

The aim of the study is to visualize the evolution of diaphragm thickness by echography during Mechanical Ventilation for patients with septic shock or acute respiratory distress syndrome and to compare with the evolution for patients under non-invasive ventilation and those with spontaneous ventilation. Measurements will be performed at day 1, day 5 and day 10 (if patient still under a mode of ventilation or in the unit).

The evolution of diaphragm thickness will also be compared to pectoralis muscle atrophy, which is not involved in ventilation, in order to assess respective effect of ventilatory inactivity and undernutrition linked to intensive care.

Inclusion Criteria:

• Age ≥18 years old
• Group 1 : under Mechanical Ventilation (time of Mechanical Ventilation for at least 5 days)
• Group 2 : under Non-invasive Ventilation
• Group 3 : Spontaneous Ventilation
• Non opposition of patient (Groups 2 and 3) or non-opposition of patient family member (Group 1)

Exclusion Criteria:

• Known diaphragmatic paralysis
• Neurologic pathology with motor deficit
• Pregnancy or breast-feeding woman